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Life in Extreme Environments.docx

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Life Sciences
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Luc Bernier

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January 14 , 2013 Life Sci 2A03: Environmental Life Sciences Life in Extreme Environments What are the Conditions Needed for Life - water o o - temperature: 0 C – 50 C - pH: 4-8 - pressure: 101.3 kPa - O2 - H2O - CO 2 Range of Tolerance - optimal range where we see the greatest abundance of organisms - zone of physiological stress: organisms are less abundant, it is much harder to remain viable - zone of intolerance: no organisms, lower limit of tolerance - does not take into account the biodiversity Phylogenetic Tree of Life - length of branches represents genetic distance between species - highlights physiological diversity Australian Desert - 12 month droughts, yet there are species of frogs that are adapted to this environment due to physiological tolerance to these conditions Atacama Desert, Chile - >1mm rain/year - yet there are bugs that thrive in this environment Antarctic Ocean - water temp: -2 Co - fish live in Antarctic Ocean tolerant to these low temperatures What Exactly is an Extreme Environment - liquid water: absolute requirement of life on Earth - life requires: energy, through a flow of electrons based on redox chemistry - redox chemistry: used to control energy flow - all the principles of organic chemistry must apply What is an Extremophile - an organisms that thrives in an extreme environment - physical extremes:  temperature  radiation  pressure - geochemical extremes:  salinity  pH - polyextremophiles: organisms adapted to more than one extreme Types of Extremophiles - acidophile: an organism that grows best at acidic (low) pH values - alkalihile: an organism that grows best at high pH values - anaerobe: thrive under conditions where there is virtually no oxygen - halophile: adapted to high salt concentration - endolith: living inside rocks or minerals - methanogen: an organism that produces methane from the reaction of hydrogen and carbon dioxide - barophile: thrive at hydrostatic pressure, over 700atm - psychrophile: thrive under very cold conditions, optimal growth at 15 C or o lower - (hyper)thermophile: thrive in warm conditions, 15 C or above, 80 C o - xerophile: thrive in low water availability Temperature - challenges  low: structural deformation by ice crystals  high: denaturation of biomolecules, ex.: chlorophyll will degrade and photosynthesis is no longer available  problems at high temperature for aquatic organis
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